Interview close who makes the final cut?

My colleage interviewed for a position within his company and has heard through the grapevine that he and the other applicant are "neck and neck." (The hiring manager asked for his performance review.) So, coming from an interviewer's perspective, how does a hiring manager make the final determination? When you have two candidates that are so close, how do you decide?

Anxiously waiting...
If it really is neck and neck it all depends. It could come down to something as simple as who lives the closest or who had a higher GPA. You just never know. Sounds like something you are just going to have to wait for the outcome of. Good luck!